The Irishman recently cited "interference with team affairs" as the reason for his departure on Wearside, and the former Manchester United captain has further lifted the lid on his time in the North-East.
He said in The Sun: "I have no problem with explaining myself. You're answerable to the people who run the club. Don't think for a minute I never spoke to (chairman) Niall Quinn.
"People have this impression that I didn't have to answer to anybody, that's rubbish.
"But people telling me what to do, when to be training, where I should be living, and that the players should be coming in with smiles on their faces. That's when there's trouble.
"The first day I was shown around I said 'people have been taking the mick out of this club for too long'.
"It was all 'we want to be winners, we want to be driven' and I tried to bring that to the club.
"Then, all of a sudden I'm told we need players to come in with a smile on their face. That's why my relationship had to end with Sunderland. I have no regrets - I'd do the same thing again tomorrow.
"I only ever smiled when I won. I worry for players who smile when they lose.
"But I do have a different mindset to millions of people on this planet, be it football or life itself."